Fog removal and prevention method utilizing cool dry air

ABSTRACT

A method for removing or preventing fog that includes taking ambient air into the confined area of a cooling chamber and subjecting the air in the confined area to cooling to reduce the temperature of the air and injecting the air that has been subjected to temperature reduction into the atmosphere above the area that is to be cleared of fog.

United States atet {72] Inventor Milton Planner 56] References Cited 21A I N g llzegsszpnng, Md. UNITED STATES PATENTS i m oflzs 969 2,362,72911/1944 Smith 62/93 35 Pawmed 971 2,969,920 l/l96l Giannoni. 239/14Assign Fairchiw Hm" Corporation 3,210,954 10/1965 Asker" 62/93Montgomery Ceunty, Md. Primary Examiner-M. Henson Wood, .lr.

[54] FOG REMOVAL AND PREVENTION METHOD Assistant Examiner-John J. LoveAttorney-Michael W. York UTlLlZlNG COOL DRY AIR 2 Chums 2 Drawing AACT:A method for removing or preventing fog that [52] US. Cl .1 239/2 R,includes taking ambient air into the confined area of a cooling 239/ l 4chamber and subjecting the air in the confined area to cooling {5 l lnt.Cl E011: 13/00 to reduce the temperature of the air and injecting theair that [50] Field of Search 239/2 R, has been subjected to temperaturereduction into the atl4; 62/93 mosphere above the area that is to becleared of fog.

A I I ID i 1 1 1 2- 18 l l 23 f l v; 20

PATENIEU Auclolsn 3,59 ,313

INVENTOR MILTON PLATTNER TTORNEY FOG REMOVAL AND PREVENTION METHODUTILIZING COOL DRY AIR This invention relates to fog removal andprevention methods and more particularly to fog removal and preventionmethods in which relatively cool air is injected into the portion of theatmosphere that is to be cleared of or kept free of fog.

Fog is generally detrimental to many activities that require goodvisibility. For instance fog greatly hampers the safe and effective useof highways, parking lots, marinas, railway marshaling yards, aircraftcarriers, and the like, and in particular aircraftrunways.

Fog that is present over aircraft runways reduces visibility and isdetrimental to the safe operation of aircraft on and over these runwaysand in many instances this fog requires the closing of the airport toincoming and outgoing air traffic, or results in the curtailing offlight operations. Due to the large numbers of incoming and outgoingflights that are handled by many airports the closing of an airport orcurtailment of flight operations due to fog results in a seriousdisruption in air traffic and this causes inconveniences to passengersand greatly increases the costs associated with airfreight and airpassenger services.

These detrimental effects of fog have been realized for some time andnumerous attempts have been made to reduce or eliminate fog. On suchattempt has involved the heating of fog-laden air and another attemptinvolved the injection of heated air into the area containing fog. Foggenerally consists of a suspension of minute water droplets in air andsince warm air has the capability of carrying a larger amount of waterin the vapor state than cooler air it would normally be expected thatthe heating of fog-laden air would eliminate the fog. Similarly, itwould normally be expected that the injection of heated air into avolume of fog-laden air would result in fog reduction by heat transferfrom warm air into the cooler fog laden air. However, in practice thesemethods of eliminating fog have not proven to be entirely satisfactory.One reason for the lack of success with these methods appears to be thatwarm air tends to rise and hence the warm air that does not contain fogdoes not stay immediately above the surface that is to be cleared of fogbut rises and permits the cooler fog-laden air to come in and cover thefacility that is to be freed of fog.

Other attempts at removing fog have included various methods andapparatus for causing the minute water droplets that form the fog tocoalesce and form large droplets which precipitate to the ground underthe action of gravity. Some of these methods and apparatus have usedsonic waves to cause the water droplets to collide and coalesce. Othermethods and apparatus have used ionized gases to create an electricfield or used charged particles to promote coalescence. Various types ofhygroscopic particles such as NaCI have also been injected into fog inan attempt to reduce fog by coalescence of the water droplets that formthe fog. Unfortunately these attempts to remove fog have not beenentirely successful and have not provided an effective system forremoving fog over such facilities as aircraft runways and the like.

The method of this invention overcomes the difficulties associated withprevious systems for fog removal and permits the effective removal orprevention of fog over aircraft runways and similar facilities.

It is therefore an object of the present invention to provide a methodfor removing or preventing fog.

Another object of the present invention is to provide a method thatprovides a volume of fog-free air that tends to remain near the surfaceof the facility that is being cleared of or is to be kept free of fog.

The present invention provides a method for removing or preventing fogin the atmosphere above an'area of the earth that is desired to becleared of or kept free of fog that includes taking ambient air into theconfined area of a cooling chamber, cooling the ambient air in thecooling chamber to produce dry cool air at a temperature that willpermit the dry cool air to be at a temperature below the temperature ofthe ambient air when the dry cool air is injected into the atmosphereand injecting the dry cool air into the atmosphere above the area of theearth that is desired to be cleared of or kept free of fog.

In order that the invention may be more clearly set forth and betterunderstood, reference is made to the accompanying drawings in which:

FIG. 1 is a plan view of an aircraft runway embodying the features ofthe present invention; and

FIG. 2 is a partial sectional view of the structure illustrated in FIG.I taken on the line 2-2 thereof.

Referring to the figures there is shown an aircraft runway areaembodying the present invention. An aircraft runway 10 is shownincluding runway approaches 11 and 12 that are located at both ends ofthe runway. Located adjacent to and on both sides of the aircraft runway10 and the runway approaches l1 and. 12 are movable vents 13 fordistributing processed air over the runway and runway approaches thatare desired to be cleared of or kept free of fog. Located at asubstantial distance away from the aircraft runway I0 and the associatedrunway approaches It and 12 is an ambient air intake 14. A heat-transferunit 15 for transferring heat into the atmosphere is located at asubstantial distance from the runway l0 and the runway'approaches II and12 on the opposite side of the runway from the air intake l4.

As best seen by referring to FIG. 2 ambient air is takeninto the airintake 14 by the suction created by a fan blade 16 that is mounted on anintake fan motor 17 that is centrally located within the air intake tube18 on struts I9 that connect the intake fan motor to the wall of the airintake tube. After the ambient air is taken into the air intake tube 18it is introduced by the action of the fan blade 16 into the confinedarea of a cylindrical cooling chamber 20 that is connected at one end tothe air intake tube and is passed through a series of cooling coils 21that are located within the cooling chamber and are part of a coolingsystem 22. As the ambient air is passed through the series of coolingcoils 21 heat is transferred from the ambient air to a coolant that islocated within the cooling coils so that cooling of the ambient air isaccomplished. This cooling causes moisture that is carried by theambient air that was introduced into the cooling chamber to precipitateout to produce dry cool air that exits from the cooling chamber 20 thatis cooler and drier than the ambient air that entered the coolingchamber. The dry cool air that leaves the cooling chamber 20 that iscooler and drier than the ambient air that entered the cooling chamber.The dry cool air that leaves the cooling chamber 20 is then passed bythe action of the intake fan blade 16 through a manifold 23 that isconnected to the cooling chamber to the series of movable vents 13 thatare connected to the manifold and are located adjacent to and on bothsides of the aircraft runway I0 and the associated landing approaches 11and 12 and is injected through the vents into the atmosphere that is tobe cleared of or kept free of fog that is above the aircraft runway andthe runway approaches.

The best results the cross-sectional areas of the interiors of thecooling chamber 20, the manifold 23, and the movable vents 13 should besufficiently large so that the cooling of the ambient air in theconfined area of the cooling chamber, the transporting of the dry coolair that is produced in the cooling chamber through the manifold and theinjecting of the dry cool air through the movable vents are accomplishedwithout substantially compressing the ambient air or the dry cool air.This is necessary since any substantial compression of the air willgenerate heat and elevate the temperature of the air that is or has beensubjected to being cooled in the cooling chamber and thus defeat thepurpose of this invention which is to introduce dry cool air into theatmosphere above an area that is desired to be cleared of or kept freeof fog.

When fog is present, the dry cool air that is injected into theatmosphere consisting of fog-laden air that is located above theaircraft runway 10 and the associated approaches II and 12 causes thefog to disperse by mixing with some of the fogladen air and causing someof the visible water that forms the fog to be converted into invisiblewater vapor. This injected dry cool air also disperses the fog byphysically replacing the moist fog-laden air. Since the dry cool airthat is injected into the area above the aircraft runway and theapproaches 11 and 12 is denser than any surrounding warmer fog-laden airthis dry cool air tends to remain over the runway and the approaches andprevents fog from forming over the runway and the approaches.

As indicated in FIG. 2 the cooling system 22 has a compressor 24 thatcompresses the coolant which is in its vapor phase, that is fed to thecompressor from the cooling coils 21 through the connecting pipe 25 andinto a series of condenser coils 26 and this generates heat. This heatof compression is then removed from the cooling system 22 by means ofthe heattransfer unit that includes a cooling fan 27 that blows air overthe condenser coils 26 and this causes the coolant to condense into aliquid. This liquid coolant is then fed from the condenser coils 26through an interconnecting pipe 28 to an expansion valve 29 where theliquid coolant is permitted to expand into a vapor within the coolingcoils 21 resulting in the transfer of heat from the air in the coolingchamber to the coolant that is being vaporized in the cooling coils.

The heated air that results from the air being blown across thecondenser coils 26 can be directed to the atmosphere or if desired itcan be used to heat building or form some other useful purpose. If theheated air is directed to the atmosphere it is important that the heatbe injected into the atmosphere at a point that is a substantialdistance away from the area that is to be cleared or kept free of fog.if desired the cooling fan 27 can be replaced by some suitable heat sinksuch as a body of cold water. if a body of water is used, the condensercoils 26 are immersed in the cold water. A variety of coolants that canbe used with this type of cooling system including NH S0,, CH CL and thelike.

It is important that the dry cool air that is injected into theatmosphere above the aircraft runway 10 and the approaches 11 and 12 beat the proper temperature for satisfactory results in removing orpreventing fog. Preferably, the cooling of the ambient air in theconfined area of the cooling chamber should be carried out so that theresulting dry cool air that is produced is at a temperature that willpermit the dry cool air to be at a temperature of about 3F. to aboutl0F. below the temperature of the ambient air when the dry cool air isinjected into the atmosphere above the area such as the runway 10 andapproaches 11 and 12 that is desired to be cleared of or kept free offog. Proper temperature control can be achieved by controlling theintake fan motor 17, the compressor 24 and the cooling fan 27. Generallyto achieve proper temperature control, the temperature of the dry coolair as it immediately leaves the cooling chamber 20 will have to belower than the temperature that the dry cool air is desired to be atwhen it is injected into the atmosphere through the movable vents 13since some heating of the dry cool air will probably take place in themanifold 13 due to heat transfer to the dry cool air through themanifold walls.

If it is desired to keep the area above the runway and the appnoachescontinuously free of fog then the fan motor 17 and the cooling system 22should be operated continuously during the time that fog conditions arepresent so that cold dry air is continuously injected into the areaabove the runway 10 and the approaches 11 and 12. If it is desired toautomatically prevent fog from being formed by the use of this inventionthe intake fan motor 17 and the cooling system 22 can be connected to asuitable data processor (not shown) that controls the motor and thecooling system and evaluates data from temperature, dew point and windsensors (not shown) that sense the conditions of the ambient air so thatthe intake fan motor and the cooling system are put into operation toprevent fog when the sensors indicate that fog conditions are likely tooccur.

This invention is suitable for removing or preventing fog in theatmosphere over a variety of facilities as well as aircraft runways.This invention can also be used to remove or prevent fog over highways,marinas, railway marshaling yards, or any area of the earth by injectingthe dry cool air in the manner previously described into the atmosphereabove the area of the earth that is desired to be cleared of or keptfree of fog.

Although the invention has been described in considerable detail withreference to certain preferred embodiments, it will be understood thatvariations and modifications may be made within the spirit and scope ofthe invention as defined in the appended claims.

What I claim is:

l. A method for removing or preventing fog in the atmosphere above anarea of the earth that is desired to be cleared of or kept free of fogcomprising the steps of introducing ambient air into a confined area,cooling said ambient air in said confined area to produce dry cool airat a temperature that will permit said dry cool air to be at atemperature about 3F. to about 10F. below the t ,mpcrature of saidambient air when said dry cool air is injected into said atmosphere andinjecting said dry cool air at a temperature about 13F. to about 10F.below the temperature of said ambient air into said atmosphere above thearea of the earth that is desired to be cleared of or kept free of fog.

2. The method of claim 1 wherein said steps of cooling said ambient airin said confined area and injecting said dry cool air into saidatmosphere are accompli'hed without substantially compressing saidambient air or said dry cool air.

2. The method of claim 1 wherein said steps of cooling said ambient airin said confined area and injecting said dry cool air into saidatmosphere are accomplished without substantially compressing saidambient air or said dry cool air.